An accurate measurement of the normal position of a patient's teeth is a critical factor in restorative and orthodontic procedures. A common technique for measuring the occlusal position is to make a mold of the teeth, or of the patient's bite, using a pliable material that can itself be hardened or that can be used to form a more nearly permanent cast. In this technique, the material is transformed into a stable gel from an initially soft plastic while in the mouth of the patient and over a period of a few minutes. The transformation can occur by chemical cross-linking or by physical gelation on cooling.
A different approach was described by one of the applicants herein in U.S. Pat. No. 4,786,254, issued Nov. 22, 1988, to Philip L. Millstein and Paul Goldberg for “Method Of Permanently Recording Occlusal Contacts”. That patent describes a method of permanently documenting an occlusal position by having a patient bite down on a thin film of pliable impression material and thereafter forming a transmission photograph of the impression material. The technique has proven useful, but its accuracy is significantly affected by the particular material used to record the occlusal markings. The extent of variability of measurements made with various tapes and impression papers is discussed in detail in Millstein, Philip and Maya, Alvaro, “An evaluation of occlusal contact marking indicators”, Journal of the American Dental Association, vol. 132, p. 1280, September 2001.